The city of Kalyazin is small and picturesque, in general, like many such cities. Nothing unusual, except for a secret institute dedicated to... the study of magic. One day, the strongest witch, the Mistress of the elements, escapes from the laboratory. Driven by hatred and a desire to avenge her imprisonment, she cuts off the city from the outside world and begins to turn the inhabitants of the city into goblins and mermaids, striving for one thing — to cleanse the real world of people and fill it with fabulous creatures. Alexey Popov decides to defeat the Mistress of the Elements in order to save his loved ones and liberate the city. Nikita Dobrynin, a blacksmith, and Ilya Muromtsev, a programmer, join him in the fight against evil. However, the Mistress of the elements is putting up serious resistance — a serious struggle for family, love and the right to remain human is unfolding in Kalyazin.